This invention relates to a device for preventing water hammer which tends to occur in various types of water piping and/or water supply equipment.
Conventionally, there have been several types of devices for preventing water hammer which causes annoying sounds in the piping and water leakage. In one type of valve, a sharp pressure change produced by water hammer is absorbed by a valve element provided with a spring or a shock absorber.
However, in these conventional devices for preventing water hammer, since the retracting volume of the valve element is proportional to a flow-in side passage pressure or an upstream side pressure, corresponding to the pressure change in the flow-in side, the neutral position is remarkably changed. Furthermore, to absorb the sharp rise caused by the water hammer, the valve element must be retracted so as to move beyond the neutral position so that the volume displaced by valve movement (hereinafter "valve movement volume") is increased, making the entire construction of the water hammer preventing device large sized.
Still furthermore, since the water hammer preventing device is devised for preventing exclusively water hammer, the device is not provided with a pressure adjusting function, namely, a function to hold the dynamic fluid pressure in the downstream passage of the device at constant pressure in normal operation.
Accordingly, it is an object of the present invention to provide a device for preventing water hammer which can resolve the above-mentioned tasks.